rule50: Judge rule50 and draw (WIP)

src/position.cpp

@@ -935,7 +935,7 @@ bool Position::check_if_game_is_over()
     }
 
     if (rule.maxStepsLedToDraw > 0 &&
-        rule50_count() > rule.maxStepsLedToDraw) {
+        posKeyHistory.size() > rule.maxStepsLedToDraw) {
         winner = DRAW;
         phase = Phase::gameOver;
         gameOverReason = GameOverReason::drawReasonRule50;

src/search.cpp

@@ -93,6 +93,9 @@ int Thread::search()
 #endif
 
     if (rootPos->get_phase() == Phase::moving) {
+        if (posKeyHistory.size() > rule.maxStepsLedToDraw) {
+            return 99;
+        }
 #ifdef THREEFOLD_REPETITION
         if (rootPos->has_game_cycle()) {
             return 3;

src/thread.cpp

@@ -143,7 +143,9 @@ void Thread::idle_loop()
             emitCommand();
         } else {
 #endif
-            if (search() == 3) {
+            int ret = search();
+
+            if (ret == 3 || ret == 50) {
                 loggerDebug("Draw\n\n");
                 strCommand = "draw";
                 emitCommand();